We begin with the renowned cancer doctor accused of poisoning the coffee of her lover and fellow doctor with deadly chemicals. Gio benitez has been tracking the story. Reporter: This twisted case involves two of the country's top cancer doctors who police say also happened to be lovers but at some point that relationship allegedly went wrong and this morning, one is accused of poisoning the other. She is one of the most famous cancer specialists in the world. Her work has won awards and been profiled by the susan g. Komen foundation. My aunt died with lung cancer when she was 35 and I was 10 so that was when I knew this is what I wanted to do. Reporter: But this morning dr. Ana maria gonzalez-angulo is at the center of a bizarre poison plot accused of adding a deadly toxin to her lover's coffee. That man, dr. George blumenschein also works at houston's renowned m.D. Anderson cancer center where patients from all over the country go for treatment. They haven't revealed a motive but in january gonzalez-angulo laced two cups of coffee with ethylene gloi coal. Criminal intent and employee tiff can be formed in a split second so we can never really know what was going on inside her head. Reporter: Blumenschein told investigators he was confused because the coffee tasted sweet even though she knew he liked his coffee black. Police say she told him the sweet flavor was just splenda. But investigators say it was poison. Blumenschein survived but says he was rushed to the e.R. With slurred speech and poor balance. What would have caused someone in such a highly respected position, someone who has worked so hard for what she has to kind of snap and do this and I think that that's going to have a lot to do with how the case basically unfolds in court. Reporter: This morning, dr. Gonzalez-angulo's attorney tells abc news she is completely innocent and that police jumped the gun. And if she did poison her lover, where would she have gotten that chemical? Investigators say you can find it in labs right at that cancer hospital. She is on administrative leave and could face 20 years behind bars if she's convicted.

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